Uart Introduction; Functional Overview - Espressif ESP8266 Technical Reference

!
11.

11.1. Functional Overview

There are two group ESP8266 UART interfaces, respectively:
UART0:
•
- U0TXD: pin26 (U0TXD)
- U0RXD: pin25 (U0RXD)
- U0CTS: pin12 (MTCK)
- U0RTS: pin13 (MTDO)
• UART1:
- U1TXD: pin14 (GPIO2)
The basic working process of transmission FIFO:
As long as there has data filling into transmission FIFO, it will immediately start sending
process.Since transmission itself is a relatively slow process,other data can be sent to the
transmission FIFO simultaneously. Data sending should be paused when the transmission
FIFO is full ,or it will cause data loss.Transmission FIFO will sent out one by one in
accordance with the order of the data filling in,until the transmission FIFO is completely
empty.Data has been sent will be automatically cleared, at the same time transmission FIFO
will be more of a vacancy.
The basic working process of receiver FIFO:
When the hardware logic receives the data, it will fill them into receiver FIFO. Program
should withdraw the data timely ,the data-dequeue is also a process of deleting data from
FIFO automatically,thus, there will be one more vacancy in receiver FIFO. If the data in the
receiver FIFO can not be removed in time, the receiver FIFO will be full which makes data
loss.
Scenario:
UART0 works as data communication interface and UART1 woks as debug port.
Espressif

UART Introduction

60 86 ! /!
11. UART Introduction
2016.05